Stop watch

Abstract

A stop watch comprising a second hand and a subsecond hand includes manually actuatable switches for producing start, stop and reset instruction signals. A first stepping motor and a first drive controller for the stepping motor drives the second hand, while a second stepping motor and a second drive controller drives the subsecond hand. The second drive controller includes a counter for counting subsecond clock pulses in response to the start signal for effecting the display of the contents of the counter by the subsecond hand in response to the stop signal.

We claim: 
     
       1. A stop watch, comprising; a first clock pulse having a period of 1 second;   a switch circuit for producing each of instruction signals of start, stop, reset and midway notice in response to the switch operation;   a first control circuit for generating a plurality of control signals in response to said midway notice instruction signal;   a first drive controlling circuit for generating first driving pulses based on said first clock pulse in response to said start and stop instruction signal, and said control signals;   a first stepping motor driven by said first driving pulses, and a first display mechanism having a second hand moved by said first stepping motor;   a second clock pulse having a period shorter than that of said first clock pulse;   a second control circuit for generating a plurality of control signals in response to the midway notice instruction from said switch circuit;   a second drive controlling circuit for generating second driving pulses based on said second clock pulse in response to the start, the stop and the reset signals generated in said switch circuit and the control signal from said second control circuit; and,   a second stepping motor driven by said second driving pulse and a second display mechanism having a subsecond hand which is moved by said second stepping motor and displays the measured time less than the unit of second.   
     
     
       2. A stop watch as recited in claim 1 wherein said first control circuit has a counter for measuring the time during the second hand is stopped to move in response to the midway notice instruction signal, and the first control circuit is constructed so as to generate a control pulse recovering the loss time for displaying when the midway notice is released. 
     
     
       3. A stop watch as recited in claim 1 wherein said second control circuit comprises a ring counter for generating the plurality of control signals. 
     
     
       4. A stop watch as recited in claim 1 or claim 6 wherein said second drive controlling has a counter for measuring a time on the basis of said second clock pulse, and the second drive controlling circuit is constructed so as to generate said second driving pulse the number of which corresponds to the measuring contents of said counter in response to the stop instruction signal or one control signal from the second control circuit. 
     
     
       5. A stop watch as recited in claim 1 wherein the period of the second clock pulse is 1/100 second. 
     
     
       6. A stop watch comprising pulse generating means for producing a first clock pulse having a period of one second and a second clock pulse having a period of a fraction of one second; manually actuatable switch means for producing at least start, stop and reset instruction signals; frist drive controlling means for producing first driving pulses corresponding to said first clock pulses in response to the start and stop instruction signals; a first stepping motor driven by the first driving pulses; a second hand driven by the first stepping motor; a second stepping motor; a subsecond hand driven by the second stepping motor; and second drive controlling means for producing second drive pulses corresponding to said second clock pulses in response to the start and stop instruction signals for driving the second stepping motor, the second drive controlling means comprising a counter for counting said second clock pulses in response to the start signal and for effecting the display of the contents of the counter by the subsecond hand in response to the stop signal. 
     
     
       7. The stop watch according to claim 6, wherein the period of the second clock pulse is 1/100 second. 
     
     
       8. The stop watch according to claim 6, wherein the switch means produces a lap time instruction signal and the first drive controlling means includes a counter for counting said first clock pulses; and further comprising first and second control means for producing a plurality of control signals in response to the lap time signal for controlling the first and second drive controlling means, respectively, to effect the display of the counters of the first and second drive controlling means by the second hand and the subsecond hand in response to a lap time signal and the counting of the first and second clock pulses by the counters of the first and second drive controlling means during the display of the lap time by the second hand and the subsecond hand. 
     
     
       9. The stop watch according to claim 8, wherein the second control means comprises a ring counter for producing the control signals. 
     
     
       10. The stop watch according to claim 9, wherein the pulse generating means produces a third clock pulse having a smaller period than the second clock pulse and wherein the first and second drive controlling means each include another counter receptive of the third clock pulses and coincident detector for generating a coincidence signal when the two counters of each drive controlling means are the same. 
     
     
       11. The stop watch according to claim 10, wherein the period of the second clock pulse is 1/100 second and the period of the third clock pulse is 1/128 second.